1. Field of the Invention
The present invention relates to an image forming apparatus employing an electrophotographic process such as a laser printer, an electrophotographic copying machine and so on, and particularly to a color image forming apparatus employing an electrophotographic process.
2. Related Art Statement
As a color image forming apparatus employing an electrophotographic process, there have been widely employed a system in which toner images are formed color by color on a photosensitive body, the resultant toner images are primarily transferred onto an intermediate transfer body to form an overcolor toner image, and the images are transferred collectively onto a paper by a secondary transfer; and a quadruple tandem system in which in four image forming stations having a photosensitive body, toner images of respective colors are formed, and the toner images of respective colors are transferred in order onto a paper being conveyed by a conveying belt.
The aforementioned intermediate transfer body and the conveying belt normally have a cleaner for cleaning the surfaces thereof attached thereto. As for the intermediate transfer body, it is necessary to mount a cleaner thereon because a transferred and remaining toner remains on the surface thereof after the secondary transfer. Further, since a large quantity of toners is stuck to the intermediate transfer body or the conveying belt, in the circumstances as stated below, it is necessary to mount a cleaner. That is, {circumflex over (1)} When the paper jam occurs, a toner image becomes remained on the intermediate transfer body or a toner image erroneously becomes formed on the conveying belt. {circumflex over (2)} Where image density adjusting is carried out, there is carried out a printing operation for forming a patch image on the intermediate transfer body or the conveying belt.
In the circumstances as stated above, since high cleaning ability is required, a blade cleaning system is employed. The blade cleaning system is the technique widely employed heretofore as a cleaning system for the photosensitive body because that system is high in cleaning ability despite the low expenses.
It is contemplated that in order to improve the cleaning ability and prevent a blade from being burred, a lubricating agent such as zinc stearate, sodium stearate and the like is coated on the intermediate transfer body or the conveying belt. However, the lubricating agent becomes necessary as a consumption article, the running cost of the image forming apparatus increases, a lubricating agent coating mechanism becomes necessary, and the coating mechanism need be replaceable, as a result of which the construction of the image forming apparatus becomes complicated. Further, when a toner image moves into the lubricating agent coating mechanism, the coating mechanism is contaminated by the toner, giving rise to a problem such that the coating ability lowers. Furthermore, in case of the intermediate transfer system, there also occurs a problem that the secondary transfer ability lowers due to the sticking of a lubricating agent depending on material for a secondary transfer roller.
Further, it is contemplated that in case of the intermediate transfer system, the cleaning blade is mounted on not only the intermediate transfer body but also the secondary transfer roller, to plan the longer service life of the secondary transfer roller, and preventing the back of paper from being contaminated. However, since the secondary transfer roller has a high elasticity and is deformed relatively greatly, there also occurs a problem that a cleaning blade for the secondary transfer roller is often burred.
The present invention has been accomplished in view of problems as noted above with respect to prior art, and has its object to provide an image forming apparatus on which is mounted a cleaning blade for cleaning the surface of an intermediate transfer body or a conveying belt, the apparatus capable of improving cleaning ability and preventing burring of the blade.
It is a further object of the invention to provide an image forming apparatus wherein even if a lubricating agent coating mechanism for coating a lubricating agent on the surface of the intermediate transfer body or the conveying belt is disposed, the lubricating agent coating ability may be maintained sufficiently without increasing the running cost.
It is another object of the invention to provide an image forming apparatus wherein in case of an intermediate transfer system, the longer service life of a secondary transfer roller and the prevention of contamination of the back of paper may be planned.
In the image forming apparatus according to the present invention, for improving the cleaning ability and preventing the blade burring, there is provided a lubricating agent coating mechanism for coating a lubricating agent on the surface of the conveying belt or the intermediate transfer body whereby when detection is made of that a cleaning blade or a conveying belt and an intermediate transfer body are new articles, or when the installation environment of the image forming apparatus is satisfied with the prescribed conditions, the lubricating agent coating mechanism is actuated to coat the lubricating agent on the surface of the conveying belt or the intermediate transfer body.
In order to make it possible to sufficiently maintain the lubricating agent coating ability also without increasing the running cost, measures are taken so that where paper jamming occurs, in the operation of returning the jammed state to a jam-free state, the lubricating agent coating mechanism is operated by a prescribed period of time to coat the lubricating agent in an area where a toner image is not formed on the surface of the conveying belt or the intermediate transfer body.
Further, for planning the longer service life of the secondary transfer roller and the prevention of contamination of the back of paper, measures are taken so that where paper jamming occurs, in the operation of returning the jammed state to a jam-free state, a toner stuck to the secondary transfer roller is transferred in reversed order to the intermediate transfer body.